1. Field of the Invention
The present invention relates to a method of network attachment with a macro eNB and a remote radio unit (RRU) by a user equipment (UE) and a UE for performing the method.
2. Discussion of the Related Art
A radio access network (RAN) configuration has been changed such that various types of small cells such as a pico cell, a femto cell, etc. interact with a macro cell. The RAN configuration refers to a heterogeneous cell configuration or a hierarchical cell configuration in which small cells for low power/near field communication coexist in addition to an existing macro cell-based homogeneous network. A new RAN configuration is used to enhance quality of experience (QoE) by providing a high data transmission rate to a last user.
In small cell enhancements for E-UTRA and E-UTRAN study item (SI) as one of 3rd generation partnership project (3GPP) standard scopes, research has been ongoing into enhancement of indoor/outdoor scenarios using low power nodes, and the scenarios is described in TR 36.932. In small cell enhancements for E-UTRA and E-UTRAN SI, research has been conduced to draw advantages of concept of dual connectivity to small cell layers and a macro cell layer in which a user uses the same or different carriers.
Considering this trend, a huge number of small cells will be deployed and thus UEs will get nearer to a network physically. Accordingly, it is expected that not conventional physical cell-based communication but communication through UE-centered zones will be conducted in a future-generation wireless access network. To implement communication through UE-centered zones to increase capacity, technical issues to realize a service providing unit such as a UE-centered zone differentiated from a physical cell-based service providing unit should be derived and solved, which will greatly affect a current RAN.